Motion detectors can form a part of an intrusion security system, but motion detectors can vary in both quality and the features that are included in the motion detector. Industry standards that describe the detection criteria and capability of motion detector features are written by the European Committee for Electromechanical Standardization: EN50131-2-2 for passive infrared (PIR) detectors and EN50131-2-4 for combined PIR and microwave detectors. The standards identify four different grades of motion detectors: Grade 1 has the lowest sensitivity and smallest feature set, and Grade 4 has the highest sensitivity and greatest feature set. Grade 1 and Grade 2 wireless detectors are known in the art. However, no wireless Grade 3 or Grade 4 motion detector exists in the marketplace.
Masking can occur when an associated motion detection system is unarmed, and any part of the motion detection system that requires a view of a monitored area can be masked. For example, if the motion detection system includes a PIR sensor, then a Fresnel lens or window that focuses heat energy onto the PIR sensor can be masked. Similarly, if the motion detection system includes an imager and a lens of the imager is exposed, then the lens can be masked. If the lens of the imager is recessed inside of a housing and covered with a transparent window, then the transparent window can also be masked.
Unlike Grade 1 and Grade 2 detectors, a Grade 3 motion detector must include an effective anti-mask system. For example, an effective anti-mask system can detect tampering with an associated motion detection system to the extent that the motion detection system can no longer detect motion. When the motion detection system includes a passive infrared (PIR) sensor, tampering that prevents the system from detecting motion can include the blocking of a lens or window to the PIR sensor with a masking material. For example, a masking material can include an IR opaque material, paper, Styrofoam, cardboard, spray paint, and clear lacquer, which allows visible light to pass, but blocks IR energy that a PIR sensor detects.
The reason that wireless Grade 3 motion detectors do not exist in the marketplace is that effective anti-mask systems, such as near infrared (NIR) emitters and detectors distributed around a lens or window, consume too much energy. When too much energy is consumed, an excessive number of batteries will be required to create a sensor with a viable battery life.
In view of the above, there is a continuing, ongoing need for a wireless Grade 3 motion detector that includes an effective anti-mask system.